Shell Rubber Research Articles

Identifying changes in the milking rubber of milking machines during testing and under industrial conditions

Milking rubber is the only part of the milking equipment that comes into direct contact with the cow’s teats. The task is to establish the high-quality technical and technological characteristics of the rubber liners for milking machines. It has been established that milking rubber after 600‒650 hours of operation acquires significant deflection in the range of 5.5±0.03–3.7±0.04 mm while a teat cup deformation varies within 1.3±0.02–3.5±0.05 mm. A positive correlation dependence of the milking rubber elasticity on the deformation of its teat cup (r=+0.948) has been found. The method of passing the electric discharge was used to assess the readiness of milking rubber for use, whereby a variation coefficient of υ˂10 % was determined for the milking rubber DD 00.041A AO «Bratslav», which makes it possible to estimate the product quality. It was found that the change in the mass and volume of milking rubber over 72 hours of its treatment with the liquid SZHR-3 at t=150 °C exceeds the indicators obtained in contact with the liquid Skydrol LD-4 by more than 2.5 times. A positive correlation dependence of the milking rubber mass on its volume (r=+0.965) has been established. It was found that at a rubber tension in the range of 0 to 90 N the duration of the deformation loss experienced by the milking rubber shell was not long; it is 0.05‒0.06 s. With an increase in the service life of milking rubber to 4 months, there is a decrease in its tension, from 56‒60 N to 43‒45 N, which adversely affects the maximum speed of milk yield – it decreases by 1.5 times. A positive correlation dependence of the milking rubber service life on the level of its bacterial insemination (r=+0.960) has been established

Fracture properties of epoxy polymers modified with cross-linked and core–shell rubber particles

To improve the toughness of epoxy polymers, cross-linked rubber (CLR) particles or core–shell rubber (CSR) particles can be blended into the epoxy matrix. Particle cavitation is thought to be the main toughening mechanism of rubber-modified epoxies. Although CLR-modified epoxies have not been studied in depth previously, it is expected that the toughening mechanism differs from that of CSR-modified epoxies because void formation is less likely to occur. We formed the CLR- and CSR-modified epoxy resins using nanosized acrylonitrile butadiene CLR particles, which showed good compatibility with the epoxy matrix and the CSR particles with a rubbery core surrounded by a glassy shell. The toughening mechanism was examined by comparing the fracture behavior, fracture surfaces, and process zones via tensile and fracture toughness testing, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and transmission optical microscopy (TOM). There was a difference in the characteristics of the R-curves between the CLR- and CSR-modified epoxies. In addition, the SEM and TEM observations indicated that there was a difference in the fracture mechanism.

Pengaruh persentase campuran kulit kayu gelam (Melaleuca Cajuputi) dan cangkang karet (Hevea Brasiliensi) terhadap karakteristik pembakaran briket

Development of alternative energy sources that can be one of the potential to produce energy in overcoming the fuel energy crisis. The availability of a lot of rubber trees and gelam bark waste in the area of South Kalimantan so it needs to be used to be processed as raw material for briquettes. In this research using a mixture of rubber shell briquettes and gelam bark waste by varying the weight percentage of the mixture. Tests carried out by burning the briquette on a heating element, to determine the characteristics of combustion in briquettes which include the time of initial ignition, the length of the combustion process, and the change in mass of the briquette to ashes. The results show the length of time of starting the ignition and the length of time the combustion process has decreased with an increasing percentage of gelam bark mixture that is during 13.7 s with a burning time of 5.54 minutes. This is due to fibrous and brittle gelam wood bark so it is flammable and contains volatile matter. High lignin content in the rubber shell leaves more ash than gelam bark which is equal to 5.75 gr Keywords : Rubber shell, gelam bark, briquettes, alternative energy, combustion characteristics.

Characterization of kaolinite/emulsion-polymerization styrene butadiene rubber (ESBR) nanocomposite prepared by latex blending method: Dynamic mechanic properties and mechanism

The latex blending method was chosen to prepare Kaolinite/emulsion-polymerization styrene butadiene rubber (ESBR) nanocomposite to improve the interaction between filler particles and rubber matrix chains. The influences of kaolinite particles size, filler contents, and flocculants types on dynamic mechanical properties and the relative reinforcement mechanism of the prepared composite were systematic investigated and proposed. The transmission electron microscopy (TEM) and scanning electron microscopy (SEM) showed that the kaolinite particles were finely dispersed into the rubber matrix and arranged in parallel orientation. The prepared nanocomposites by latex blending exhibited improved crosslinking characteristic and dynamic mechanical parameters. The KAl (SO4)2 flocculant presented obvious modification in dynamic properties and crosslinking characteristic. Both the decrease in kaolinite particle size and the increase in kaolinite content can greatly improve the storage modulus and reinforcing effect of kaolinite/ESBR nanocomposites. The dynamic reinforcement mechanism of kaolinite can be explained by filler network including a certain thickness of rubber shell on the surface of kaolinite lamellar structure and the aggregations network between kaolinite particles The optimum way to balance the dynamic properties of rubber nanocomposites at different temperatures is to reduce the surface difference between kaolinite and rubber matrix and the degree of filler-filler networking on the basis of kaolinite with nanoscale (nanometer effect).

Copolymer Distribution in Core–Shell Rubber Particles in High-Impact Polypropylene Investigated by Atomic Force Microscopy–Infrared

High-impact polypropylene (HIPP) is an important and industrially relevant material with a complex morphological structure. In this paper, two commercial resins with similar rubber contents are inv...

The use of tapered double cantilever beam (TDCB) in investigating fracture properties of particles modified epoxy

This study compares fracture energy of an epoxy polymer from the addition of different wt% of nanoparticles, for both experimental and FEA modelling studies. Silica and core–shell rubber (CSR) particles, and the hybrid of both (from 0.5 wt% to the maximum concentration of 25.4 wt%) are used. An increase in fracture energy was found in the CSR and hybrid specimens, but clustering of particles caused a reduction in the mechanical properties when the concentration of particles was high. As there was interfacial failure found with some tapered double cantilever beam (TDCB) specimens. Therefore, the fracture energies measured with TDCB specimens are also compared with simulation results using the finite element analysis software ‘Abaqus’. These results provided further information for the next stage of investigations in fracture properties of particles modified epoxy.

The Effect of Different Acrylic-Based Rubbers on the Crystallization Behavior of PLA/PDLA Stereocomplex

This study investigated the performance of two acrylic rubbers on the improvement of mechanical and thermal properties of polylactic acid (PLA)/ poly(D-lactide) (PDLA) stereocomplex. The selected acrylic-based rubbers consisted of a commercial acrylic rubber (ACM) and acrylic core–shell rubber (CSR). In this work, 5 wt% PDLA was melt-blended with PLA to form PLA/PDLA stereocomplex (ST) in the presence of a 15 wt% acrylic-based rubber in an internal mixer at 180 °C and 50 rpm. It was found that the small amount of PDLA could successfully form stereocomplex crystals with PLA during melt mixing. The addition of acrylic-based rubbers not only increased the impact strength of the blends but also assisted PLA in forming more perfect crystals. This is because the rubbers could act as nucleation sites for PLA crystallization leading to smaller spherulite size than that of neat unmodified PLA. Comparatively, CSR could provide much higher %crystallinity with quicker nucleation onset than ACM in both PLA and ST systems, even though the crystallization rate was lower. In terms of mechanical properties, CSR also contributed to the highest impact strength due to the smaller size of CSR than ACM in both PLA and ST systems.

Epoxy based hybrid nanocomposites: Fracture mechanisms, tensile properties and electrical properties

This work explore the effect of addition of a combination of rigid nanofillers and core–shell rubber nanoparticles on the fracture mechanics, tensile, electrical and thermo-mechanical properties of epoxy resins. SiO2 nanoparticles, multi-walled carbon nanotubes (MWCNT's), as rigid nanofillers, and core–shell rubber (CSR) nanoparticles, as soft nanofillers were used with bisphenol-A based epoxy resin. Further, the rigid fillers were added systematically with core–shell rubber nanoparticles and MWCNT’s to study the combined effect of rigid nanofillers and soft CSR nanoparticles. The resulting systems will be characterized by standard methods. This includes a thorough characterization of tensile, fracture mechanics, electrical, and thermal properties. The results show that the maximum increase of fracture toughness (207%) and fracture energy (910%) was obtained for system containing 5 wt% of CSR and 10% SiO2. The electrical conductivity threshold was obtained at 0.075 wt% of MWCNT’s modified system. The introduction of CSR nanoparticles significantly increase the fracture energy of the matrix with decrease in tensile strength and tensile modulus, which was further recovered with the addition of SiO2 nanoparticles. The analysis of the fracture surfaces revealed the toughening micro-mechanisms.

Study of rubber composites between natural rubber and Mahogany Shell Powder (MHSP) and potential for pavement block

This research was aimed to study the feasibility of using mahogany fruit shell powder as filler in rubber and investigated in properties of obtained vulcanized rubber. As mahogany fruit shell contains 75.61% holocellulose, 13.54% lignin and 11.02% extractives [1]. Hence the fruit shell should be able to act as reinforcement in rubber materials [2]. In this study, mahogany fruit shell was milled into small particles with the particle size of approximately 60 micrometres follow by ASTM D 422 - Standard Test Method for Particle-Size Analysis of Soils. The particle was characterized for their thermal stability. The morphology of mahogany fruit shell powder, MHSP, was flake like particle and can be used as reinforcement fillers in natural rubber. As NR is generally sensitive to O2 thus ethylene propylene diene monomer, EPDM, would be laminated on the top of NR/MHSP composites. The rubbers were formulated with efficient vulcanization system and contain 10, 20, 30, 40 and 50 phr of MHSP. The rubber compounds were characterized for cure characteristic parameter such as scorch time, cure time, minimum and maximum torque. Rubber vulcanizates were prepared using compression molding and characterized for their morphology, mechanical properties, thermal degradation, hardness and weathering resistance. In order to improve environment stability and abrasion resistance of the NR/MHSP composites, EPDM/MHSP were prepared and laminated on NR/MHSP and vulcanized. The laminated vulcanizated composites possessed the properties follow Thai Industrial Standard for rubber paving blocks could be obtained. The results also showed that NR filled with 50 phr of MHSP in NR and in EPDM gave the properties follow the standard and has high potential for outdoor rubber paving block.

Design of high impact thermal plastic polymer composites with balanced toughness and rigidity: Toughening with core-shell rubber modifier

It is different from one phase impact modifier such as ethylene-propylene rubber (EPR), ethylene-propylene-diene monomer copolymer (EPDM), polyolefin elastomer (POE) et al., that the core-shell rubber particles constructed by a hard core and a soft shell is a typical two phases impact modifier. They have been successfully and widely introduced to toughen polymers by melt blending or alloying in reactor. However, an important but unclear question is how to obtain the high impact thermal plastic polymer composites with less rigidity loss by optimizing the structure and the properties of the core and shell phases. To answer this question, we develop the model from one phase modifier to two phases modifier and make a quantitative calculation in this study and obtain the following results: (1) In order to obtain the high impact polymer composites with low rigidity loss, the modulus of the core should be as higher and the modulus of shell should be as lower as they can; (2) Comparing to one phase impact modifier, core-shell rubber particles toughened polymer composites can have less rigidity loss. The lowest modulus loss for the high impact PP can decrease from 26.1% for one phase modifier, to 13.5% for the core-shell modifier with PE core, and to 5.4% for the core-shell modifier with PP core; (3) The impurity, i.e. the rubber shell contains homo PP or PE and the core contains EPR, leads to the increase of the rigidity loss for the high impact PP alloys in reactor.

Wearable Device Oriented Flexible and Stretchable Energy Harvester Based on Embedded Liquid-Metal Electrodes and FEP Electret Film.

In this paper, a flexible and stretchable energy harvester based on liquid-metal and fluorinated ethylene propylene (FEP) electret films is proposed and implemented for the application of wearable devices. A gallium liquid-metal alloy with a melting point of 25.0 °C is used to form the stretchable electrode; therefore, the inducted energy harvester will have excellent flexibility and stretchability. The solid-state electrode is wrapped in a dragon-skin silicone rubber shell and then bonded with FEP electret film and conductive film to form a flexible and stretchable energy harvester. Then, the open-circuit voltage of the designed energy harvester is tested and analyzed. Finally, the fabricated energy harvester is mounted on the elbow of a human body to harvest the energy produced by the bending of the elbow. The experimental results show that the flexible and stretchable energy harvester can adapt well to elbow bending and convert elbow motion into electric energy to light the LED in a wearable watch.

Anomalously enhanced toughness of poly (lactic acid) nanocomposites by core-shell particles with high thickness soft shell

The anomalous improvement in ductility and toughness of biodegradable poly (lactic acid) (PLA) was achieved by incorporating the silica-g-poly(caprolactone-co-lactide) (SiO2-PCLLA) core-shell nanoparticle with high thickness rubber shell. The variation of mechanical properties and toughening mechanism of nanocomposites with rubber shell thickness were investigated via tensile tests and surface morphology observation, X-ray scattering (SAXS) and diffraction (WAXD). The experimental results showed that the core-shell nanoparticle with high thickness rubber shell of 25 nm extremely remarkably improved the ductility and toughness of nanocomposite, about 34 times higher than those of neat PLA, particularly nearly without reducing its strength. This considerable increment of toughness is attributed to that the cavitation occurred in thick rubber shell can induce the intense plastic flow of matrix, forming the fibrillated structure like ‘bamboo joint’. In addition, it was found that the toughening of PLA is not only related to the rubber shell thickness, but also to the added nanofiller content.

The effect of polylactic acid (PLA)/poly‐d‐lactidestereocomplex on the thermal and mechanical properties of various PLA/rubber blends

AbstractThis study investigated the effect of polylactic acid (PLA)/poly‐d‐lactide (PDLA) stereocomplex (ST) on the improvement of the mechanical and thermal properties of various rubber‐toughened PLAs. In this work, natural rubber (NR), synthetic polyisoprene rubber (IR), silicone rubber (SI), acrylic rubber (ACM), acrylic core–shell rubber (CSR), thermoplastic copolyester (TPE) and thermoplastic polyurethane (TPU) were chosen as the toughening agents. 5 wt% PDLA was melt‐blended with PLA to form ST crystals in the presence of 15 wt% rubber in an internal mixer at 180 °C and 50 rpm. It was found that the melting temperature of ST crystal (Tm,sc) and the impact strength of ST/rubber blends were strongly correlated with the rubber domain size. For the blends of ST with compatible rubbers (ACM, CSR, TPE and TPU), the rubber domain sizes tended to be smaller with higher Tm,sc and higher impact strength than the blends with incompatible rubbers (NR, IR and SI). However, the presence of ST crystals in PLA/incompatible rubber blends, especially the blends with NR and IR, led to a significant increase in the rubber domain size and plunges in tensile toughness and impact strength. On the other hand, the presence of these crystals in PLA/compatible blends did not change the rubber size or the impact strength significantly compared with those without ST crystals except in the case of ST/ACM, which resulted in a large increase in the impact strength. Among all rubber types, CSR provided the highest impact strength for both the PLA and ST systems. © 2019 Society of Chemical Industry

UJI EFEKTIFITAS ASAP CAIR CANGKANG BUAH KARET (Hevea braziliensis) SEBAGAI ANTIBAKTERI Bacillus subtilis

The purpose of this research was know the effectiveness quid smoke the liquid smoke of the rubber (Hevea braziliensis) shell.The manifacture and purification of liquid smoke is carried out by 4 stages: pyrolysis, sedimentation, distillation, redestilate. The first of the research is calculating phenol levels, total acid, pH, and type weights The results showed that the feeding of rubber (Hevea braziliensis) shell liquid Smoke proved to inhibit the growth of bacteria Bacillus subtilis where the higher the concentration of liquid smoke, the greater the resistance. The phenol levels contained in the liquid smoke of the rubber shells were obtained at 0.84% with a total acid rate of 4.725%, and a pH at 2.548 and a density at 1.004. Antibacterial test using disc paper with see diameter clear zone. Bacterial using is pure cultur Bacillus subtiis bacteria. The concentration liquid smoke to antibacteral test is 5%, 10%, 15%, 20% and 25%. Of the five treatment obtained KHM 20% with diameter clear zone is 5,21 mm. Analysis results using One Way ANOVA obtained F hitung ? f tabel then there Significant differences Against the resulting clear zone.

Mechanical properties and fracture behavior of high‐performance epoxy nanocomposites modified with block polymer and core–shell rubber particles

ABSTRACTThe mechanical properties, thermomechanical properties, and fracture mechanic properties of block‐copolymer (BCP), core–shell rubber (CSR) particles, and their hybrids in bulk epoxy/anhydride system were investigated at 23 °C. The results show that fracture toughness was increased by more than 268% for 10 wt % BCP, 200% for 12 wt % of CSR particles, and 100% for hybrid systems containing 3 wt % of each, BCP and CSR. The volume content of nanoparticles influences the final morphology and thus influences the tensile properties and fracture toughness of the modified systems. The toughening mechanisms induced by the BCP and CSR particles were identified as (1) localized plastic shear‐band yielding around the particles and (2) cavitation of the particles followed by plastic void growth in the epoxy polymer. These mechanisms were modeled using the Hsieh et al. approach and the values of GIc of the different modified systems were calculated. Excellent agreement was found between the predicted and the experimentally measured fracture energies. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48471.

Hygrothermal conditioning of wet-layup CFRP-concrete adhesive joints modified with silane coupling agent and core-shell rubber nanoparticles

The adhesive bond between externally bonded fiber-reinforced polymer (FRP) repairs and the concrete substrate can significantly deteriorate under hygrothermal conditions. The present study evaluated the epoxy adhesive toughening with core–shell rubber (CSR) nanoparticles and concrete surface functionalization with an epoxy-functional silane coupling agent as a means of improving the bond durability under hygrothermal exposure. To determine the effect of environmental degradation, beam bond test specimens were subjected to control conditions (standard laboratory conditions: 23 ± 2 °C and RH 50 ± 10%) and a hygrothermal accelerated conditioning protocol (ACP) (water immersion at 45 ± 1 °C) for 8 weeks. Bond test results indicate that CSR toughening and silane coupling agent can improve FRP-concrete adhesive bond strength retention following accelerated conditioning by up to 15% over that of neat epoxy. Following accelerated conditioning, CFRP coupons prepared with CSR-modified epoxy retain their mechanical properties, while the CFRP prepared with the neat epoxy exhibited a significant reduction in strength (40%) and elongation (54%). CSR nanoparticles demonstrated good compatibility with the base epoxy resin, as evidenced by differential scanning calorimetry (DSC) glass transition temperature measurements.

Fracture and toughening mechanisms of silica- and core\u2013shell rubber-toughened epoxy at ambient and low temperature

The highly cross-linked thermosetting polymers used as adhesives and as the matrices of fibre composites for the construction of lightweight vehicles are very brittle, and finding effective toughening solutions for such engineering applications is a long-standing problem. An anhydride-cured thermosetting epoxy polymer has been modified by the addition of different wt% of silica nanoparticles, core–shell rubber particles and hybrids with equal wt% of both. The fracture energy was measured at ambient and low temperature (− 40 °C and − 80 °C) to understand the brittle fracture behaviour. The fracture and toughening mechanisms were identified by scanning electron microscopy of the fracture surfaces. Analytical models were used to predict the modulus and fracture energy; the predictions agreed very well with the measured values. Toughening using silica nanoparticles is especially efficient at low particle contents. This shows how epoxies can be toughened successfully for use in industrial and transport applications.

PEMANFAATAN LIMBAH CANGKANG BIJI KARET DENGAN ADITIF TEMPURUNG KELAPA SEBAGAI BAHAN BAKAR ALTERNATIF MELALUI TEKNOLOGI PEMBRIKETAN

The development of alternative energy sources that can replace fuel oil is very important to utilize natural resources optimally and environmentally. The shell produced from rubber plants is the main ingredient in this study, while the coconut shell is an additional material used to increase the calorific value of alternative fuels which is often referred to as Briquette. The purpose of this study is to determine the effect of variations in raw material composition and variations in pressure on the quality of rubber shells and coconut shell waste briquettes according to SNI standards. The raw material for rubber shell and coconut shell is processed into charcoal using carbonization method with a variation of a mixture of 85%: 15%, 90%: 10% and 95%: 5% with 5% adhesive. Then mix the printed material with a pressure of 300 kg/cm2 and 100kg/cm2. The quality parameters of briquettes are based on SNI 01-6235-2000 standards with moisture content, ash content, volatille matter content, and lacquer value. The results of the study showed that the sample b1 with 85% injection: 15% print pressure 300kg/cm2. The briquette with the sample code b1 has a water content value of 5,10432%, ash content of 14,8604%, volatile matter content of 12,8002%, carbon value of 66,8225% and heating value of 6576.592501 cal/gr. But overall the briquettes have not met the standards of SNI 01-6235-2000 concerning the quality of wood charcoal briquettes. Because the ash content of the briquette exceeds the maximum limit that has been determined, namely a maximum of 8%. Keywords: Alternative Energy, Rubber Seed Shell, Coconut Shell, Pressure

Effect of core–shell rubber toughening on mechanical, thermal, and morphological properties of poly(lactic acid)/multiwalled carbon nanotubes nanocomposites

ABSTRACTThe effect of core–shell rubber (CSR) toughening on mechanical and thermal properties of poly(lactic acid)/multiwalled carbon nanotubes (PLA/CNT) nanocomposites were investigated. The nanocomposites were prepared by direct melt blending method in a counter‐rotating twin‐screw extruder. The contents of CSR were varied between 5 and 20 wt % while the content of CNT was kept at 5 phr. The extruded samples were injection molded into the desired test specimens for mechanical and thermal properties analysis. The impact strength of PLA/CNT increased with increasing CSR content with concomitant decrease in tensile strength and modulus. Interestingly, the flexural strength increased at low CSR content before decreasing at 15 and 20% content. Differential scanning calorimetry analysis on the second heating cycle shows no crystallinity content for PLA/CNT and all CSR toughened PLA/CNT nanocomposites, while thermogravimetric analysis shows lower thermal degradation of all CSR toughened PLA/CNT as compared to PLA/CNT nanocomposite. This study reveals significant correlation between CSR loading with the mechanical and thermal properties of the nanocomposites. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2019,136, 47756.

Resistance to Cleavage of Core⁻Shell Rubber/Epoxy Composite Foam Adhesive under Impact Wedge⁻Peel Condition for Automobile Structural Adhesive.

Epoxy foam adhesives are widely used for weight reduction, watertight property, and mechanical reinforcement effects. However, epoxy foam adhesives have poor impact resistance at higher expansion ratios. Hence, we prepared an epoxy composite foam adhesive with core–shell rubber (CSR) particles to improve the impact resistance and applied it to automotive structural adhesives. The curing behavior and pore structure were characterized by differential scanning calorimetry (DSC) and X-ray computed tomography (CT), respectively, and impact wedge–peel tests were conducted to quantitatively evaluate the resistance to cleavage of the CSR/epoxy composite foam adhesives under impact. At 5 and 10 phr CSR contents, the pore size and expansion ratio increased sufficiently due to the decrease in curing rate. However, at 20 phr CSR content, the pore size decreased, which might be due to the steric hindrance effect of the CSR particles. Notably, at 0 and 0.1 phr foaming agent contents, the resistance to cleavage of the adhesives under the impact wedge–peel condition significantly improved with increasing CSR content. Thus, the CSR/epoxy composite foam adhesive containing 0.1 phr foaming agent and 20 phr CSR particles showed high impact resistance (EC = 34,000 mJ/cm2) and sufficient expansion ratio (~148%).